This invention relates to a syringe having a rectractable cannula. More particularly, this invention relates to a hypodermic syringe which may be used for administering serum, antibiotics, or the like, and in which the sharp pointed cannula thereof is retractable subsequent to injection to avoid contamination and injury.
Current hypodermic syringes present a problem in that the sharp-pointed cannula thereof frequently causes injury and infection subsequent to the administration of the medicinal fluid contained within the syringe. Typically, a hypodermic syringe is used in the form of a disposable, preloaded syringe of plastic material having a barrel and a piston reciprocable by means of a plunger therein. A sharp-pointed cannula is fixed to the forward end wall of the syringe barrel and is protected by means of a removable plastic sheath. A difficulty is encountered subsequent to injection of the fluid when the protective sheath is attempted to be replaced over the cannula. Frequently, the person administering the injection inadvertently becomes stuck by the now-contaminated cannula. This can cause the spread of various diseases, including hepatitis. In any event, it is costly to hospitals and other medical facilities in terms of time and administration costs. Typically, an incident report has to be filled out for each such inadvertent wounding. In addition, a hepatitis shot may have to be given to the person so wounded.